Overexpression of MMP9 is a clear feature of triple-negative and HER2+ breast cancers [12] and studies have suggested that MMP9 appears to be an important target for the triple-negative subtype of breast cancer [13], as beside overexpression, it is also involved in extracellular-matrix remodeling, plays a direct role in the expansion of tumor cells, and promotes tumor metastasis [10]. The gene discussed is MMP9; the disease is breast cancer.